Is Delhi’s AQI 400 or 2000? Why the two different readings are both right

Delhi’s air turned toxic after Diwali, with confusion over its actual pollution level. India’s Central Pollution Control Board (CPCB) pegged the city’s AQI near 351, while Swiss air-quality monitoring firm IQAir’s readings soared beyond 2,000. We explain the stark difference — and why both figures reveal the same alarming truth: Delhi’s air is hazardous